Many propositions have been advanced regarding orthopaedic external fixator devices, which comprise basically the adjustable mounting of assembly mechanisms connecting different parts of a fractured bone and permitting its management and setting in the desired position.
As an example of these orthopaedic external fixator devices we can mention Soviet Pat. No. 227511, with international classification A61B 17/18, which favours an orthopaedic external fixator composed of five half-rings joined in pairs by slotted small plates to which there are fixed transfixion wires going over the bone in a lineal form within the same plane on both sides of the fracture's core. The system already formed has a mechanism of screws which allows the fracture to be tractional or compressed when being actioning actional over the hoops.
Soviet Pat. No. 827049, international classification A61B 17/18, favours an orthopaedic external fixator composed of four half-rings held within their elements to pass the transfixion wires, which can move together in the plane supporting them every time the mechanism of screws that join the half-rings by pairs is rotated one.
The Czechoslovakian Pat. No. 503050, international classification A61B 17/18, favours an orthopaedic external fixator composed of half-rings containing in their ends elements carrying transfixion wires and screws which also serve to fit and join the half-rings. When actioned they permit their separation or reciprocal shortening together with the wires transfixing the bone on both sides of the fracture core.
As the nearest prototypes we have the orthopaedic external fixator favored by the Soviet Pat. No. 227511, international classification A61B 17/18, which is composed of four half-rings joined by pairs with slotted small plates containing elements coupled to them with transfixion wires crossing lineally over the bone in a common plane. It also includes an actioning mechanism placed conveniently between the inner half-rings, which allows the traction or compression of the bone.
The Soviet Pat. No. 910153, international classification A61B 17/18, favours an orthopaedic external fixator formed by two rings with joint rods between them having transfixion wires crossed in parallel planes to fix the bone. A dispositive serving as a support to hold the patient's limb and the orthopaedic external fixator during surgery is also shown. Soviet Pat. No. 227511 presents technical imperfections such as: (1) having to mobilize the whole fixator structure during the operation of traction or compression of a fracture makes the fixator a little bit unstable; (2) the slotted small plate containing the elements that fix the transixion wires on their ends brings less rigidity to the system and this could damage the pathological bone.
The mechanisms for moving the ring parallel during traction or compression of a fracture is very complex since it contains many elements.
Regarding the Soviet Pat. No. 827049, the external fixator device has the technical disadvantage of having a transfixion point per each ring, so when its wire in connection with the bone is loosened, the apparatus will easily displace laterally, thus acting against the bone consolidation process.
The Czechoslovakian Pat. No. 593050 presents the same technical difficulty since the action of traction or compression of a fracture with this system implies that all rings together have to be moved, thus bringing less stability to the unit.
Concerning Soviet Pat. No. 910153, the fixator has the technical disadvantage of having the wires transfixing the bone crossing in a common plane, thus making the fixator lose mechanical qualities in that zone. The rings bring ambulatory discomfort to the patient. A special support table is essential for its location during the surgical process. It is also necessary to guarantee the ring parallelism during the process of compression or traction in order not to create power components that would deviate it from its course.
The objectives of the invention are: (a) the creation of an external fixator device whose simplicity could make the labor of the specialist easier during surgery and its later follow-up; (b) to make possible that it can be used with satisfactory results in: compression, traction, epiphysial and diaphysial fractures, stabilization, arthrodesis, pseudoarthrosis, etc.